<!doctype html>
<html>
<head>
</head>
<body>
    <h1>Custom Page</h1>
    <button onclick="native()">click</button>
    <script>
        // called when the runtime is ready
        var Module = {
            onRuntimeInitialized: function () {
                alert('onRuntimeInitialized');
            }
        };

        // called from main()
        function onLoaded() {
            alert('Module is loaded');
        }

        function native() {
            var content = Module.ccall('world', 'string');
            alert(content);
        }
    </script>
    <script async type="text/javascript" src="hello.js"></script>
</body>

</html>